单盒钠冷快堆燃料组件堵流事故的CFD分析

钠冷快堆大都采用金属绕丝来固定燃料组件，细长狭窄的流道容易积聚腐蚀沉积物，可能会引起钠的局部沸腾和包壳的传热恶化。本文利用商用计算流体动力学软件STAR-CCM+程序对中国实验快堆单盒燃料组件的堵流事故进行了数值模拟，分析了包壳内壁面温度与冷却剂在堵块附近的轴向流场分布，并与正常工况下的计算结果进行对比。计算结果表明：实心介质堵流危害比多孔介质更为严重；实心介质堵流事故的包壳峰值温度局部最高点始终位于堵块中心位置，而多孔介质堵流事故的位于堵块后方，且随堵块面积的增大而往下游偏移；堵块的孔隙率对包壳在堵块下游的最大温升有明显影响，随堵块孔隙率的增大而减小。

CFD Analysis on Flow Blockage Accident of Single Subassembly for Sodium Cooled Fast Reactor

Sodium cooled fast reactors mostly use metal wires to space the fuel assembly, and slender and narrow flow channels are easy to accumulate corrosive sediments, which tends to cause the local sodium boiling and heat transfer deterioration of cladding. In this paper, single subassembly blockage accidents were numerically simulated by the commercial computation fluid dynamics (CFD) software STAR-CCM+, temperature of cladding inner face and coolant axial velocity distribution around blockage were analyzed and compared with the result in no-blockage case. The calculation results show that the harm of solid media blockage is more serious than that of porous media. The local highest point of cladding peak temperature is always located at the centric position of the blockage in the solid media blockage accidents. But in the porous media blockage accidents, the cladding peak temperature is found in the downstream of blockage and tends to move further downstream with the increase of blockage area. The blockage porosity is seen to exhibit significant influence on the maximum cladding temperature difference in the downstream of blockage. Further, the maximum cladding temperature difference is smaller if the porosity is larger.